Sunday, 15 June 2008

Natural pollination of Cannas

Canna pollination is basically trivial in practice. Hold a flower stem steady and smear some pollen onto the stigma of the style. Roughly six weeks later, there's a pod of ripe seeds if all has gone well. But there are some good reasons to know more and do more, because sometimes our efforts fail. Sometimes we want to do more than just a self-pollination, and make crosses between different cultivars, and sometimes even cross with species.

Pollination means transferring pollen from the anther onto the stigma of the flower. In the case of canna the hard part has already been done, and the pollen has been squeezed out of the anther and is waiting for us on the style. If we do not perform a hand pollination, then an obliging pollinator will almost certainly do it instead.

Pollen contains the male reproductive cells of a plant. Canna pollen, is heavy and sticky, and has a high protein content. It cannot be blown in the wind, so it must be gathered and distributed by insects or other active pollinators. You can laugh if anyone claims that canna gives them hay fever, as the only way you could get canna pollen in your nasal passages is to stick a flower up your nose. The plants trade some food to the bees in exchange for the transfer of pollen, called pollination.

The easy way
Most of the large canna hybridizers let the honey bees do their ad-hoc pollinating for them, although they do tend to isolate and plant varieties of interest together, this is why this blog pays a lot of attention to the honey-bee. The benefits of this type of planting are many:

  • lots of seed.

  • no worry about compatibility.

  • no expensive hands-on care.
The downside is that only one parent is known for certain, and in our experience we have also found a much lower proportion of 'special' flowers. With hand pollination many more of your resultant offspring can be uniquely 'special'. The small, home garden hybridiser just doesn't have room for a lot of poor seedlings. On the other hand he or she can provide the daily attention that will yield specific crosses for specific goals and a high proportion of special blooms.

Further information on hand-pollination will follow.

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